And it turned out to be a great change from Mourinho as Fellaini popped up with United's winner in the 92nd minute of the game.

Just before Fellaini and Martial came on Mourinho could be seen instructing them on the sideline and United's match winner told Sky Sports what Mourinho said to them.

"He told me to go in to the box because I have the possibility to keep the balance with the midfielder," Fellaini said. "One point wouldn’t have been too bad but in the end we have three points and that’s most important today."

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Mourinho explained why he made the decision to bring on Fellaini over the other players on the bench.

"I knew they were going to block and normally with 1-1 a good result for them they were going to drop the block and without Lukaku it would be more comfortable for them to drop the block," Mourinho told Sky Sports.

"I felt we needed a second presence, in this case the first presence was Martial as he would stretch the defenders we would get some superiority on the sides because Alexis was coming inside too much and Martial was more wide with Ashley Young and creating problems on the side.

"Then Marouane scored a beautiful goal which mathematically qualifies us for the Champions League."